The Influence of Land Surface Temperature (LST) in Actual Evapotranspiration Estimated

Document Type : Research Paper


1 Department of Irrigation and Drainage, Department of Water Engineering, Shahid Chamran University of Ahvaz

2 Lorestan University _ Assistant Professor, Department of Water Engineering, Faculty of Agriculture and Natural Resources

3 Soil and Water Research Institute, Department of Irrigation and Soil Physics, Karaj

4 Department of Water Engineering, Faculty of Agriculture, Lorestan University, Lorestan, Iran.



The remote sensing technique is one of the methods for estimating actual evapotranspiration (ETa), which is a suitable option for estimation of ETa at the large-scale due to spatial and temporal resolution. The present study aims to assess the ETa using the SEBAL algorithm and different algorithms to survey the effect of the LST and their impact assessment on the ETa fluctuation. Field measurement, including canopy temperature and the volume of inflow and outflow of water consumption was done based on lysimeters during 2018-2019. After the necessary pre-processing on the satellite images, the Land Surface Temperature (LST) was estimated using Planck's and split window algorithms. The result shown that the performance of Split window was better than to the Planck algorithm. Also, ETa was estimated by the SEBAL algorithm based on two temperature scenarios including the Planck and split window. The results shown, the cold pixel of SEBAL algorithm have compliance with the Lysimetric measurement. Moreover, the cold pixel of the split window algorithm with RMSE=0.56, NRMSE=0.084 and NS=0.992 (mm/day) have the highest consistency with the lysimeter data. Also, the rMBE index of the split window algorithm was associated with underestimation in the range of -4.07 to -3.22%, while the Planck function algorithm fluctuated with overestimation in the range of 4.76 to 12.65%. This research is verify to the cold pixel of the satellite which crop no stress conditions and for better investigation at crop stress condition we need precise instrument.


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